Tappet



G. SLAYTER Feb. 5, 1935.

TAPPE'I' Filed NOV. 15, 1930 lllIfi INVENTOR i/mas $u1rrzm BY A W7 ATTORNEYS lIllll Patented Feb. 5, 1935 Games Slayter,.Deti'oit, Mich. I I r V v Application November 15, 1930, Serial No. 495,937

' "mm. (o1. 123-190 I i I This inventionrelates to, a tappeh s uch a's is usedin connection with valve operating mechani'sm in internal combustion engines, and has to P the strain applied by the mechanic.

Many different ways have been proposed for strengthening the threaded end of the tappet to withstand the rough usage usually encountered at this point, and one method has been to spot weld a steel bearing jacket on to a castiron head. While this has proven to be a practical solution of the problem, such a tappet has necessarily'been relatively expensive to manufacture.

It is the object ofthe present invention to provide means for positively preventing cracking or twisting of the connecting end of the tappet when wrenches are applied to tighten the adjusting nuts in place. More specifically, the present invention embodies the use of a steel crown adapted to be so secured around the end of a tappet formed mostly of cast iron as to prevent cracking or twisting of the cast iron.' In this case the steel jacket not only takes the greater part of the strain from torsional stresses applied to the tappet but acts as a. band'around the end thereof to reinforce and prevent any splitting at the point of'application'of the torsional stress.

In the drawing:

Fig. 1 is a longitudinal sectional view illustrating the manner of fabricating the cast iron tappet and one form of steel crown therefor.

Fig. 2 is an elevation, partly in section, of th assembled tappet.

Fig. 3 is a sectional view taken on line .33.of

Fig. 2, and showing the preferred manner of cutting away a portion of the jacket and the cast iron wall whereby to receive a wrench or similar adjusting tool.

Fig. 4 is a fragmentary enlarged view, partly in section, and illustrating a modified form of jacket wherein the parallel sides are completely formed in the cast iron.

Fig. 5 is a sectional view illustrating a further modification wherein the steel jacket forms a threaded portion of the tappet but is connected the-threaded portioni fl i, 1 Fig.6 is a view si'rnilar'to -Fig';' 3 but illustrating a; modified mariner of seciiringthe 'steel jacket to the cast ironshe11.-**

to the tappet at a point-jin'iri1 e'diately adjacent The gist of thep'resent invention r'eside's in the forming" or the-greater part Of the tappet; and

infact substantially all of the tappet, of cast iron and the adding of a small inexpensive steel crown for positively reinforcing and holding the tappet as an integral unit at the point'of greatest application of stress and strain. By forming the main body of the tappet of cast iron it is possible to chill the side walls as well as the head of the tappet if desired so as to present a very inexpensive but efficient bearing surface.

As shown in the embodiment illustrated in Figs. 1 and 2, my tappet preferably consists of a main body portion which may be generally designated 1. This body portion is formed of cast iron and having a standard head 2 with a chilled bearing surface 3 and cylindrical side walls 4 adapted to fit in the tappet sleeve. The interior of the cast iron body 1 may be cored out or drilled as at 5 and provided with the usual threads 6 for receiving the threaded end of the adjusting member as in standard practice.

The Walls 4 of thetappet may or may not be chilled and ground to present an accurate bearing surface. It will be understood that if. the walls 4 should be formed of steel as has been done in the past, it would be necessary to heat treat such steel surfaces to present the proper this steel crown are heldto very close dimen sions so as to preferably have a press fit with i the turned down walls 7.

It: will be, understood that the capping of the cast iron tappet with, the crown 8 may be made by any well known method, that is, the crown may be sweat in place, it may be shrunk upon the walls 7, or it may have a press fit therewith.

The manner in which the crown 8 is secured to,

the end of the cast iron tappet is immaterial as the important point here is that the end of the tappet is reinforced by a steel crown for positively preventing the same from splitting. The

is usuaiiy applied at a point adjacent the threaded end thereof with the result that in the use of standard cast iron tappets excessive torsional stress placed on the end thereof frequently causes cracking. The steel crown 8 is therefore posicut away the steel crown as at 11 with the result that a wrench applied to the surface 11 will contact both with the cast ironbody and the steel crown. It will thus be obvlous-.,that considerable torsional stress may be appliedbythe wrench but the end of the cast iron sleeve be securely held against cracking bythesteel crown. I

In the modification illustrated min le I have 1 shown the reduced wall '7 of the cast iron sleeve as being serrated whereby to cooperate with complemental serrationspformed on thev innerwall of the steel crown as shown. at-12; In this case if the power should be applied only at points 13 the complemental serrations will preventany twisting of the crown relative to the cast iron body.

In the modification illustrated in Fig. 4 the cast iron body 1 is fabricated toinclude the cut away portions 14 for receiving a wrench, the steel.

crown 15 just having sufiicient depth to cap the end of the cast iron body. In'this case the steel crown takes none of the direct torsional stress applied by the wrench but acts solely as a-re inforcing-band for preventing cracking of the cast iron;

In the modification illustrated in Fig. a steel I crown 16 while still forming a relatively small vpart of the entire tappet is considerably longer than the crowns shown in Figs. 1 and 2. In this modification the bearing portion of the tappet is formed by the cast iron but a portion of the threads and the cut away surfaces'for receiving'the wrench are formed in the steel crown.

What I claim is:

1 A tappet having the greater ;portion thereof formed of castiron, a st eel crown forone end of said tappetandbearing surfaces formed partly: by said cast iron and partly by said crown forrec eiving an adjusting tool.

, GAMES SLAYTER. 

